Internet Service Provider (ISP) networks contain routing and switching equipment that connect users to other endpoints in the same ISP network or to endpoints in other ISP networks. Internet Service Providers generally do not like users forming end-to-end connections through their networks that cannot be monitored. For example, the ISP network may include firewalls, that need to monitor all incoming connections in order to prevent unauthorized network access. Other equipment, such as Network Address Translators (NATs), may also need to monitor user connections in order to convert between public and private Internet Protocol (IP) addresses.
Network connections may also need to be continuously monitored in order to diagnose network problems. For example, when two endpoints establish an end-to-end session, the ISP has limited visibility to the communications transferred between the two users. This may prevent the ISP from debugging subsequent network failures.
End-to-end user connections arguably make it more difficult for the ISP to manage Quality of Service (QoS) for different types of data or for different users. With end-to-end connections, the user machines generally have the responsibility for requesting and monitoring QoS. Without ISP system level QoS management, a user may request higher QoS than is necessary for certain types of media communications. This may disrupt other media communications that do require high QoS, such as a real-time VoIP phone calls.
The Resource ReSerVation Protocol (RSVP) is a path coupled signaling protocol that goes from one endpoint to an opposite endpoint and through every router between the two endpoints. The routers install states associated with the type of service requested by the users. When all the routers along the media path indicate a level of requested service can be provided, the endpoints are notified that admission control has succeeded and the reserved media path is then used for transporting media.
RSVP is not preferred by many ISPs partly because it typically is initiated by the users. As mentioned above, it is perceived by the ISP as a loss of control over QoS management. Further, many user host devices, such as personal computers, may not implement RSVP, which would then prevent any admission control of QoS service for the media call.
Session Border Controllers (SBCs) are currently being used to manage signaling and media at the edges of ISP networks. The SBC may conduct signaling sanitization that removes certain information from the call signaling, such as public IP addresses, caller ID information, etc. The SBC may also modify information, such as converting private IP addresses to a public NAT addresses. The SBC may also modify QoS service bits for media packets.
If ISPs adopted end-to-end path-coupled admission control signaling, there would be little need for SBC media plane functions. However, as described above, Multiple System Operators (MSOs) require and have adopted additional QoS control such as provided by Dynamic Quality of Service (DQoS) and Packet Cable Multi-Media (PCMM). This QoS control utilizes an SBC to provide admission control at multiple points along the media path.
In order to do so, the SBC must have topological knowledge of the media paths. This is inconvenient, can be a performance bottle-neck and usually results in poor responsiveness to routing changes or outages.
Thus, the SBC is required to sit in both the control path and data path for each network flow that requires ISP management. The SBC intercepts all application signaling and inserts itself in both the signaling and the media path established by the associated application. This requires the applications used for establishing media connections to communicate directly with the SBCs. For example, a Session Initiation Protocol (SIP) or H.323 signaling session is required to conduct signaling for every VoIP call through the SBC. In addition to the signaling, the audio data for the VoIP call must also be routed through the same SBC.
This management architecture causes several problems. For example, when the SBC fails, all the media sessions managed by the SBC are terminated. This compromises reliability for the overall ISP network. End-to-end media security is also broken, since the SBC requires access to the session encryption keys in order to manage the data in the media session.
When centralized in the ISP network, the SBC becomes a hotspot, since all communications needs to be routed through the same node. Inefficient routing problems remain even when SBCs are distributed out toward the user access locations. For example, routing algorithms have to be reconfigured to route all communications through the remote SBCs. This causes media to be routed along suboptimal network paths. For instance, instead of using optimized routing algorithms that may establish a relatively direct Internet connection between two closely located endpoints, the IP connection may have to be routed through two SBCs that are located in geographic locations remote from both endpoints. This is not only inefficient, but may also introduce significant extra delay, which is highly disadvantageous for delay-sensitive applications such as VoIP.
The present invention addresses this and other problems associated with the prior art.